Tuesday, June 25, 2013

Regular Menstrual Periods May Not Be Triggered By Regular Ovulation

I came across this article on WEBMD. Just Because you have a regular cycle dose not mean you ovulate each month.

Secrets of the Ovary Revealed -– Part Two
In the first part of our series on the secrets of the ovary, we learned that ovulation may or may not switch sides every cycle. Now let’s look at the relationship between ovulation and regular menstrual periods.
Regular Menstrual Periods May Not Be Triggered By Regular Ovulation
A woman can have apparently regular flows and yet still not be having regular ovulation. How can this happen? In a cycle without an ovulation, estrogen stimulation (assisted by the hormone FSH ) will continue to make the lining of the uterus grow thicker and thicker. In the absence of an LH (luteinizing hormone) surge, no ovulation will occur. The progesterone level will not rise. When the follicle that contains the un-ovulated egg involutes (shrinks), the woman’s blood estrogen level will drop. This triggers much of the lining to be shed. Thus if it takes two to three weeks for the follicle and un-ovulated egg to regress, the woman may have somewhat regular bleeds.
How often does this happen? In the first year after menstrual periods begin, up to 55% of the cycles may occur without ovulation (Mansfield & Emans, 1984). In a study of 20-35 year old women who had regular cycles but were infertile, an average of 30% of women were not ovulating. Among these 123 women with regular cycles the highest incidence of not ovulating was 41%. This highest incidence occurred among women who had never had a conception. Women who had at least one documented pregnancy had a lower incidence of non-ovulation despite regular periods (Hegab, 1987).
Finally, the presence of very regular periods, accompanied by common premenstrual symptoms (“molimena”) suggests an ovulatory cycle — especially when there are menstrual cramps. Yet this may not always be the case. In as many as 5% of these “classic for ovulation” cycles, ovulation may not have occurred (Speroff, 1999).

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